Heterogeneous mobile radio system

ABSTRACT

The invention relates to a heterogeneous mobile radio system ( 1 ) for providing services from a packet data network for a mobile terminal (MT) ( 7 ). Said system comprises at least one first mobile radio network ( 2 ) and one second mobile radio network ( 3 ). Said mobile radio networks ( 2, 3 ) respectively comprise at least one access node ( 4, 5 ) to the packet data network, and the access node ( 5 ) of the second mobile radio network ( 3 ) can only be indirectly connected to the packet data network via the access nodes ( 4 ) of the first mobile radio network ( 2 ). The invention also relates to a method for providing services from a packet data network for a mobile terminal ( 7 ) of a mobile radio system, said method comprising the following steps: (a) at least one first ( 2 ) and one second ( 3 ) mobile radio network respectively comprising at least one access node ( 4, 5 ) to the packet data network are provided; and (b) the mobile radio networks ( 2, 3 ) are combined in such a way that data packets can only be indirectly transported between the second mobile radio network ( 3 ) and the packet data network via the access nodes ( 4 ) of the first mobile radio network ( 2 ). The invention further relates to a mobile terminal ( 7 ) for using a heterogeneous mobile radio system comprising at least one first mobile radio network ( 2 ) and one second mobile radio network ( 3 ). Said mobile terminal ( 7 ) can simultaneously maintain connections to the first ( 2 ) and the second ( 3 ) mobile radio networks.

[0001] The present invention relates to a heterogeneous mobile radiosystem having at least one first and one second mobile radio network,with each of the two mobile radio networks each having an access node toa packet data network. Public mobile radio networks, in particular 2G/3Gnetworks, are designed to offer services in parts of the countrydistributed as widely as possible. In this case, a situation can occurin which the available capacity for the demanded services is notadequate in certain regions, that is to say in certain cells, and inparticular when there is a high subscriber density within these regionsor cells. The problem is further exacerbated by the capabilities beingprovided for new services with wide bandwidths, such as multimedia, bymeans of the mobile access systems to the Internet, for example by meansof the packet data service GPRS (General Packet Radio Service) in mobileradio networks based on the GSM Standard or UMTS (Universal MobileTelecommunications System).

[0002] The problem is worse in locations and buildings such as airportsor exhibition halls, in which it can generally also be assumed that thesubscribers are moving at a relatively slow speed. In this case, by wayof example, the two approaches described in the following text couldlead to a solution to this problem.

[0003] It would be feasible to install very small cells, that is to saymicrocells or picocells, using the same technology as the overallnetwork, for example in conjunction with overlay or umbrella cells. Withthis procedure, the subscriber would not notice any sign of theintervention, that is to say the installation of additional cells in theoverall network, that is to say the installation would be completelytransparent to the mobile radio network subscribers. Furthermore, theinstallation of such very small cells would fit seamlessly into theoperating concept of the mobile radio network operator. There would beno transmission losses or undesirable interruptions in transmission.Furthermore, in general, no special measures would be required forcharging and/or authentication of the corresponding mobile radio networksubscribers. However, the installation of such very small cells in theoverall system would be very expensive, involving very expensive radiotechnology since a very high degree of mobility is supported.Furthermore, possibly, the network could be heavily loaded withsignaling traffic, since the small cells would lead to a large number ofhandovers between the cells. In this case, the radio technology could beconstrained by its limits, in particular with regard to the transmissionfrequencies.

[0004] Furthermore, it would be feasible to install an alternativewire-free access system to the Internet. By way of example, this couldbe a wireless LAN (Local Area Network), Bluetooth or similar systems.The advantage in this case would be that it would actually createadditional transmission capacity. Furthermore, the installation of suchalternative systems is in general not as costly as the installation ofvery small cells that have been mentioned. However, one disadvantageousfeature is the fact that seamless handovers from the 2G/3G mobile radionetwork to the alternative mobile radio network would be impossible, orfeasible only to a restricted extent. This means that losses andinterruptions in the transmission could occur. In a situation where, forexample, the WLAN (Wireless LAN) is associated with a different networkoperator than the 2G/3G mobile radio network, the subscriber mustauthenticate himself for a second time with the WLAN, that is to say theinstallation of an alternative mobile radio network is not transparentto the subscriber. If, on the other hand, the WLAN is operated by thesame network operator as the 2G/3G mobile radio network, then thisnetwork operator would at least have to introduce new methods forauthentication and for charging for operation, and this would increasethe operating costs of the system.

[0005] Until now, solutions on IP layers have normally been chosen, inorder to create heterogeneous mobile radio systems such as a combinationof a 2G/3G mobile radio network with a WLAN, providing IP traffic. Theexpression IP layer in this case refers to protocols in the InternetProtocol (IP) family which are independent of the transmission technique(for example LAN or WAN) and the access technique (mobile radio,landline network). One of the most widely discussed solutions in thiscase is mobile IP corresponding, for example, to RFC2002 for IP-v4. TheInternet access in 3GPP 2G/3G networks is generally provided on thebasis of 3GPP TS23.060. Access nodes (GGSN: Gateway GPRS Support Nodes)are in this case provided which in each case provide access to theInternet and support the appropriate Internet Protocol (IP). In thiscase, a fixed reference point for the Internet is provided at the GGSN,at which each subscriber can be accessed using an IP address. Within thecore network, that is to say within the actual mobile radio network, themobility between the access network nodes (GGSN) and the existingservice network nodes (Service GPRS Support Node: SGSN) is provided viaGTP tunneling. The entire connection between a mobile terminal (MT) andthe access node GGSN together with the control data that describes theconnection is referred to as a packet data protocol (PDP) context. Asubscriber can be accessed by corresponding subscribers via a fixed IPaddress which is made available to him, for example, by an InternetService Provider (ISP). When this subscriber now registers in a 2G/3Gnetwork, he is provided with a preferably dynamic IP address by anInternet Service Provider. In this case, this Internet Service Providerand the mobile radio operator of the 2G/3G network may beorganizationally identical. The following procedure would be requiredfor a subscriber to change between the 2G/3G network and the WLAN bymeans of mobile IP: the subscriber must register with his home agent inthe Internet from the 2G/3G mobile radio network using his IP address.This Home Agent (HA) may be provided by a second (home) ISP. Thesubscriber can be accessed at this HA via a fixed IP address or via someother identification in the network of the second ISP. The data packetsare then tunneled via a mobile IP (MIP) tunnel from the home agent tothe access node GGSN for the IP address for the subscriber in the 2G/3Gmobile radio network. In order to ensure that the packets are passed tothe mobile terminal (MT) of the subscriber, a foreign agent (FA) must beprovided in the GGSN in order to cancel the encapsulation of the packetstunneled to that GGSN and to send them to the mobile terminal with afixed associated home address. When the subscriber registers in the WLANand there is likewise a foreign agent (FA) in a WLAN controller which isacting as the access node to the Internet, then the home agent in theInternet can also pass on the packets by means of mobile IP (MIP)directly into the WLAN controller. The advantage of this solution isthat the subscriber can keep his IP address when changing betweensystems, so that there is no need to interrupt many applications.However, as already mentioned initially, it has the disadvantage thatnew methods and/or measures for access authorization control andcharging would need to be introduced or implemented in the area of theWLAN. If the possibility of changing between the two mobile radionetworks and the two access systems, as described here between a 2G/3Gmobile radio network and a WLAN, were to be offered as a service by thenetwork operator of the 2G/3G mobile radio network, this operator wouldalso have to provide the home agent as well as home IP addresses for hissubscribers, since the home agent controls and provides routings for thepackets to the MT. Furthermore, the subscriber identifications andcharging data for the respective networks must be correlated. Thistherefore leads to considerable operator complexity. Furthermore, itwould possibly lead to longer switching times owing to the protocol,because registration data and authentication data would need to beinterchanged between the MT, FA and servers for authentication,authorization and charging (AAA) and HA. Furthermore, longer switchingtimes can result if there is a long distance between the home agent andthe local area networks in which the mobile subscriber is located.

[0006] One object of the present invention was now to provide a mobileradio system which at least has the advantages of both approaches thathave been mentioned, but at the same time overcomes their disadvantages.

[0007] This object is achieved by the mobile radio system according tothe invention as claimed in claim 1. Further preferred embodiments arespecified in the appropriate dependent claims.

[0008] According to claim 1, a heterogeneous mobile radio system forprovision of services from a packet data network for a mobile terminal(MT) is provided, having at least one first mobile radio network and onesecond mobile radio network, with the mobile radio networks each havingat least one access node to the packet data network, and in which casethe access node for the second mobile radio network can be connected tothe packet data network only indirectly via the access node for thefirst mobile radio network.

[0009] In one preferred embodiment of the heterogeneous mobile radiosystem, the packet data network is the public Internet.

[0010] According to the invention, at least one first mobile radionetwork is now combined with a second mobile radio network, with bothmobile radio networks each having at least one access node to a packetdata network, preferably to the Internet. In the situation where thefirst mobile radio network is a 2G/3G mobile radio network, the accessnode is formed by a GGSN (Gateway GPRS Support Node). In the secondmobile radio network, for example a WLAN, the access node with thefunctions according to the invention is referred to as a Local MobilityAgent (LMA). Via an IP router function, these access nodes represent aninterface to a packet data network, preferably to the landline IPnetwork, and act as access routers, that is to say they terminate mobileradio- and access technique-specific protocols. IP protocols, inparticular mobile IP (MIP), can also advantageously be used for thispurpose. According to the invention, the access node for the secondmobile radio network is now not connected directly to the packet datanetwork, preferably the Internet, but all the data is tunneled via theaccess node to the first mobile radio network.

[0011] Furthermore, at least one agent function can be integrated in theaccess node for the first mobile radio network. In one preferredembodiment of the mobile radio system according to the invention this isa home agent function, preferably a routing function. The routingfunction is therefore moved from the packet data network, preferably theInternet,

[0012] into the first mobile radio network, preferably into a 2G/3Gmobile radio network. This avoids the operation of a home agent in thepacket data network or in the Internet, and the allocation of fixed IPaddresses in the Internet. The IP address in the mobile radio system canbe retained when changing between a first and a second mobile radionetwork. There is therefore no interruption between the applications,and the routing is considerably improved.

[0013] In one preferred embodiment of the heterogeneous mobile radiosystem according to the invention, the first mobile radio networkrepresents an overlay network for the second mobile radio network. Inthis case, a supply by the first mobile radio network is also ensured inthe supply areas of the second mobile radio network. It is particularlypreferable for the first mobile radio network to be a 2G/3G mobile radionetwork. In this case, a connection between the first mobile radionetwork and a mobile terminal is not given up even when using the secondmobile radio network, that is to say the mobile terminal is “always on”in the first mobile radio network. Owing to the presence of an overlaynetwork, it is accordingly possible to use one or more functions of thefirst mobile radio network for the second mobile radio network, as well.For example, an authentication function for the first mobile radionetwork, preferably a 2G/3G mobile radio network, is also used for asubscriber to the mobile radio system, and a charging function for thefirst mobile radio network, preferably a 2G/3G mobile radio network, isalso used for the second mobile radio network, preferably a WLAN. Thishas the advantage that the mobile radio system subscribers need notauthenticate themselves more than once, that is to say they need notreauthenticate themselves once again when changing between the twomobile radio networks, even when they wish to use both mobile radionetworks. Furthermore, this allows all subscribers who have access tothe first mobile radio network, preferably to the 2G/3G mobile radionetwork, to use the services on the second mobile radio network,preferably a WLAN. This may also relate to roamers from other mobileradio networks who have access to the first mobile radio network.Furthermore, a low-cost technique, in particular an Internet technique,can in this way be used for the second mobile radio network, preferablya WLAN, since this technique need not have any authentication functionor any charging function. For the network operator of the mobile radiosystem, this results in no change, or little change, to the operator oroperation concept. The second mobile radio system, preferably a WLAN,can be introduced seamlessly into the overall system, that is to saywithout any interruption and without any losses. Since all of thetraffic for the second mobile radio network is also passed via the firstmobile radio network, there is sufficient information in the firstmobile radio network to allow very flexible charging. Thus, for example,a volume of data which is transmitted in the second mobile radionetwork, preferably a WLAN, can be charged for in an identical way to avolume of data which is transmitted in the first mobile radio network,preferably a 2G/3G mobile radio network. Furthermore, it may, however,also be at no charge, or may be charged at the tariff of an Internetservice provider. In the latter case, this allows any desired legaldemands or business cases to be satisfied. Authentication andauthorization of a subscriber for use of the second mobile radio networkcan be carried out in the first mobile radio network by carrying out theregistration process for the second mobile radio network via the firstmobile radio network, and by the access node for the first mobile radionetwork comparing the subscriber address (IP) to be registered for amatch with the IP address of the subscriber in the first mobile radionetwork, and checking for the presence of a corresponding PDP context inthe first mobile radio network.

[0014] In a further preferred embodiment of the heterogeneous mobileradio system, when using a home agent function, in particular a mobileIP home agent function, data which can be specified can be selectivelytransmitted only via the second mobile radio network.

[0015] When using the GTP protocol, the data path between the accessnode for the second mobile radio network and for the first mobile radionetwork can be implemented by a generalization of the existing“secondary PDP context” concept of GPRS, with the packet distributionfunction for secondary PDP contexts being used in order to distributedata traffic between the first mobile data network and the second mobileradio network, as well, in which case the tunnels, when seen from theGGSN, may have different destination addresses.

[0016] Furthermore, when using the mobile IP home agent function in theaccess node for the first mobile radio network, this does not justswitch all of the traffic between the first mobile radio network and thesecond, but it is also possible to pass only specific data records viathe second mobile radio network, in accordance with any trafficclassification which may be provided. This corresponds to an extensionof MIP.

[0017] Furthermore, the mobile IP registration can be extended forsignaling of the setting up of a connection between the access node forthe second mobile radio network and for the first mobile radio network,to be precise by session-specific data for the PDP context for the firstmobile radio network, for example by subscriber and context identities,and by session-specific data for setting up the tunnels between theaccess node for the second mobile radio network and for the first mobileradio network, such as data stream characteristics for trafficclassification as in the TFT for GPRS. It is thus possible, for example,to use the second mobile radio network for voice over IP or multimediaconnections, while the first mobile radio system can be used for therest of the data traffic.

[0018] The first access node advantageously provides coupling betweenthe PDP context for the second mobile radio network and a context in thefirst mobile radio network. Furthermore, it preferably allows thecontext in the second mobile radio network only when there is at leastone context in the first mobile radio network.

[0019] A control function is preferably provided in the access node forthe second mobile radio network, and causes data packets which are to besent from the second mobile radio network to be transported exclusivelyto the access node for the first mobile radio network. This can beachieved, for example, by using specific IP addresses for the tunnel endpoints between the first and the second mobile radio network.Furthermore, specific address allocation techniques can be used formobile subscribers in the second mobile radio network. In addition, thiscan also be monitored by a test for predefined access addresses of thetunnel destination address of the access node for the first mobile radionetwork in the access node for the second mobile radio network.

[0020] The second mobile radio network may be operated by the operatorof the first mobile radio network, or else by a different operator. Evenin the second case, the operator of the second mobile radio network neednot carry out any subscriber management, that is to say need not provideany authentication function or subscriber charging. A type ofinteroperator charging can be carried out for billing purposes with theoperator of the first mobile radio network, for example for the entirevolume of data which is transported for the network operator of thefirst mobile radio network.

[0021] In a situation where a 2G/3G mobile radio network as the firstmobile radio network is combined with a WLAN mobile radio network as thesecond mobile radio network, the entire connection from a mobileterminal (MT) to a GGSN in the 2G/3G mobile radio network, including theconnection via the WLAN, can be implemented as an extension to the GPRSsecondary PDP context. This is regarded as being the capability of amobile terminal to set up two or more connections to the GGSN using oneIP address. These connections may then differ in particular in thequality of service (QoS), such as the guaranteed bandwidth. For example,it is possible to handle standard Internet traffic such as WEB browsingand e-mail in a first context, and to handle a voice over IP telephonyconnection in a second (secondary) context. This results in only a smallnumber of technical changes, for example in the GGSN, for the 2G/3Gmobile radio network.

[0022] The heterogeneous mobile radio system according to the inventiondoes not require any new protocols and can operate with already knownprotocols such as MIP and/or GTP. In particular, the control between amobile terminal and the respective access node can be carried outexclusively using mobile IP. This allows control using standard IETFtechniques, and no system-specific changes are required.

[0023] Since, in the situation where the mobile radio network is anoverlay network for the second mobile radio network, the connectionbetween the first mobile radio network and a mobile terminal is notgiven up even when using the second mobile radio network, it is stillpossible to transmit security-relevant or safety-relevant data via thefirst mobile radio network. While, for example, Internet downloads arecarried out via the second mobile radio network, preferably a WLAN, theasymmetry of the traffic in the downlink direction is also carried outby the first mobile radio network, preferably a 2G/3G mobile radionetwork.

[0024] Furthermore, the present invention also relates to acorresponding method for provision of services from a packet datanetwork for a mobile terminal in a mobile radio system, with the methodhaving at least the following steps:

[0025] a. provision of at least one first and one second mobile radionetwork, each having at least one access node to the packet datanetwork;

[0026] b. combination of the mobile radio networks such that datapackets can be transported between the second mobile radio network andthe packet data network only indirectly via the access node for thefirst mobile radio network.

[0027] Data packets which are to be sent from the second mobile radionetwork are preferably transported by means of a control function in theaccess node for the second mobile radio network, exclusively to theaccess node for the first mobile radio network.

[0028] A further object of the invention was to provide a mobileterminal for use of a heterogeneous mobile radio system having at least

[0029] one first mobile radio network and one second mobile radionetwork.

[0030] This object is achieved by the independent claim 13. Furtheradvantages of the mobile terminal according to the invention arespecified in the dependent claims 14 and 15.

[0031] According to claim 13, a mobile terminal is provided according tothe invention, for use of a heterogeneous mobile radio system having atleast one first mobile radio network and one second mobile radionetwork, in which case the mobile terminal can simultaneously maintainconnections to the first and to the second mobile radio network.

[0032] The mobile terminal can preferably selectively transmit data viathe first and/or via the second mobile radio network.

[0033] A subscriber to the heterogeneous mobile radio networkadvantageously maintains a connection simultaneously in the first and inthe second mobile radio network. In consequence, no data can be lostwhen a handover occurs. The data relaying function that is normallyotherwise used for this purpose during a handover in the mobile radionetwork is not required here, since the mobile terminal can carry outthis function. The switching of data streams from the first mobile radionetwork to the second mobile radio network and vice versa [lacuna] thetransmission end is signaled in the respective mobile radio network, inorder to make it easier for the mobile terminal to protect the sequenceof the data.

[0034] In a further preferred embodiment of the mobile terminal, datastreams which are transported via the first and second mobile radionetwork can be combined in the mobile terminal.

[0035] Data streams which are transported via the first and the secondmobile radio network are preferably combined in the mobile terminal.This considerably reduces the handover function in the mobile radiosystem. Since the connection between the first mobile radio network andthe mobile terminal is preferably not given up, only a partial handovertakes place between the first and the second mobile radio network, as aresult of which the amount of data which needs to be transmitted betweenthe mobile radio networks is minimal, and the handover signaling isgreatly simplified.

[0036] The subject matter of the invention relates essentially to theembedding of a second alternative mobile radio network in a first mobileradio network, preferably in a 2G/3G mobile radio network such as theGPRS.

[0037] In summary, the advantages of the present invention are, inparticular, that the heterogeneous mobile radio system according to theinvention results only in a partial handover between the mobile radionetworks. The handover functions are moved to the mobile terminal. Theinvention allows a generalization of the concept of the secondary PDPcontext to be implemented. Furthermore, a home agent function ispreferably combined with an access node, preferably with a GGSN.Furthermore, according to the invention, a control function ispreferably combined with the access node for the second mobile radionetwork, forcing the data packets to be routed to the access node forthe first mobile radio network.

[0038] Further advantages of the heterogeneous mobile radio systemaccording to the invention and of the method according to the inventionwill be explained with reference to the following figures, in which:

[0039]FIG. 1 shows a schematic illustration of a heterogeneous mobileradio system according to the invention, with a connection for theInternet;

[0040]FIG. 2 shows a detailed schematic illustration of a furtherheterogeneous mobile radio system according to the invention, with aconnection for the Internet.

[0041]FIG. 1 shows a heterogeneous mobile radio system 1 according tothe invention, which has a first mobile radio network 2, preferably a2G/3G mobile radio network such as a GSM-GPRS and/or UMTS-GPRS, and asecond mobile radio network 3, such as a WLAN. The first mobile radionetwork 2 has an access node 4, a GGSN in the case of GSM-GPRS and/orUMTS-GPRS, in which a home agent function is integrated. The secondmobile radio network 3 likewise has an access node 5. Both access nodes4, 5 act as access routers. A data tunnel 6 is formed between the accessnodes 4 and 5. In order to make it possible to set up this data tunnel6, a mobile terminal 7 must signal the address of the access node 4 forthe first mobile radio network 2 to the access node 5 for the secondmobile radio network 3. There are various possible ways to do this.Firstly, the access node 4 for the first mobile radio network 2, forexample a GGSN, can distribute its address or the home agent address viathe first mobile radio network 3, preferably a 2G/3G mobile radionetwork, using MIP, which is referred to as home agent advertisement, orthe mobile terminal 7 can use MIP to check the address, a so-called homeagent solicitation. In the latter case, the access node 4, preferablythe GGSN, responds to this request with its own address, and does notdistribute it any further to other routers. The information interchangebetween the access node 4 and the mobile terminal 7 may also be carriedout using other protocols or protocol extensions. Furthermore, however,the address of the access node 4 may also be a component of the PDPcontext data that is stored in the mobile terminal 7. It is alsofeasible for the mobile terminal 7 to know only the address of one node(which is serving the terminal 7) in the first mobile radio network 2,but once again to know the address of the access node 4. The mobileterminal 7 sends the address of the node which is serving the terminal 7to the access node 5, and the latter checks the serving node for thefirst mobile radio network on the basis of the address of the accessnode 4.

[0042]FIG. 2 shows a more detailed illustration of a furtherheterogeneous mobile radio system according to the invention. Twovariants of the mobile radio system according to the invention will nowbe described in the following text with reference to FIG. 2.

[0043] In the first variant, a packet distribution function 9 isimplemented in an access node 4 for the first mobile radio network 2,preferably in a GGSN, as an extension to the secondary PDP contextconcept of GPRS. A mobile terminal 7 registers in the first mobile radionetwork 2, in the illustrated case in a 2G/3G mobile radio network.Furthermore, the mobile terminal 7 has set up at least one PDP contextto an Internet service provider 8, from whose address area it receivesan IP address (in the following text: IP-mt). This context is regardedas “always on”, in order to ensure the accessibility of the mobileterminal 7 and to make it possible to interchange at least signalingmessages for specific services with the Internet. The mobile terminal 7can set up further secondary PDP contexts for the same IP address inorder, for example, to reserve bandwidth, particularly at the radiointerface, for specific services. The traffic which is intended for asecondary PDP context is in this case described by a traffic flowtemplate. This is a parameter set which characterizes specific datastreams and allows a packet distribution function 9 in the GGSN toclassify the data packets appropriately and to allocate the respectivedata streams, that is to say (secondary) PDP contexts. The mobileterminal 7 identifies the presence of a second alternative mobile radionetwork 3 and decides to use it. To do this, the mobile terminal 7 setsup a connection to the access node 5 for the second mobile radio network3. In the present case, the latter is a WLAN, and the access node 5 isin this case referred to as a local mobility agent (LMA). From there, itreceives an IP address. The mobile terminal 7 signals to a packetdistribution function 9 in the GGSN 4 that it wishes to provide theInternet service for its IP address IP-mt via the second mobile radionetwork 3. This can be done both via the 2G/3G mobile radio network 2and via the WLAN 3. For signaling via the WLAN 3, the mobile terminal 7signals a request using MIP or other protocols to the LMA 5, whichconverts this request to a so-called create PDP context request message.The mobile IP request may have a session-specific extension added to itin order to provide the LMA 5 with the required session parameters forsetting up the PDP context from the LMA 5 to the GGSN 4. To do this, itindicates as destination addresses for the tunnel end points the GGSN 4and its own address. In consequence, the connection is set up betweenthe LMA 5 and the GGSN 4. Control messages from the 2G/3G mobile radionetwork 2 are used for signaling via the 2G/3G mobile radio network 2.The available mechanisms, for example an activate secondary PDP context,must be extended for this purpose in order to make it possible totransmit the address of the LMA 5 to the GGSN 4 and to indicate to acorresponding service network node in the 2G/3G mobile radio network 2that no new context is intended to be set up. The GGSN 4 then sets up anew tunnel 6 to the LMA 5 with a corresponding tunnel endpoint address.This tunnel 6 can use the GTP protocol as an encapsulation technique,with this representing the lowest level of GGSN functions that need tobe changed. All of the downlink traffic is then passed via this tunnel6. End of service signaling can be carried out on the old data path 10in order to simplify the data coordination in the mobile terminal 7. TheGGSN 4 carries out the charging for the new data path, that is to sayvia the tunnel 6, as an extra, characterized, for example as a new QoSclass. As soon as the new data path has been set up via the tunnel 6, itcan also be used by the mobile terminal 7 for the uplink traffic. TheLMA 5 tunnels all the uplink data to the GGSN 4. The mobile terminal 7can be controlled by appropriate setting of a traffic flow template inorder to determine whether all of the data or only a specific portion ofthe data is transmitted from the GGSN 4 to the terminal 7 via the mobileradio network 2.

[0044] In the second variant, a packet distribution function 9 isprovided in the GGSN 4 by means of an integrated home agent 9, which hasa direct interface to the GPRS functions of the GGSN 4. The mobileterminal 7 is registered in the 2G/3G mobile radio network 2 and has setup at least one PDP context to an Internet service provider 8, fromwhose address book it receives an IP address (in the following text:IP-mt). This context is once again regarded as “always on”, in order toensure the accessibility of the mobile terminal 7 and in order tointerchange at least signaling information for specific purposes withthe Internet. The mobile terminal 7 can set up further secondary PDPcontexts for the same IP address in order, for example, to reservebandwidth, in particular at the radio interface, for specific services.The IP-mt is automatically entered as the home address in the integratedhome agent 9. The mobile terminal 7 identifies the presence of a secondalternative mobile radio network 3, and decides to use it. To do this,it sets up a connection to the LMA 5, from where it receives an IPaddress. The mobile terminal 7 signals to a packet distributor 9 and/orto the home agent 9 in the GGSN 4 that it wishes to provide the Internetservice for its IP-mt via the LMA 5. This may be done both via the 2G/3Gmobile radio network 2 and via the WLAN 3. The signaling via the WLAN 3to the LMA 5 is carried out as already described in the first variant.Mobile IP is preferably used for the LMA 5 to the GGSN 4. During thesignaling via the 2G/3G mobile radio network 2, an MIP request can besent as normal L3 IP traffic, with the home agent address correspondingto the GGSN address. One advantage in this case over signaling via theWLAN 3 is that a protected and authenticated path is used. The GGSN 4has to filter out MIP messages which are directed to it from the userdata stream, and pass these to the internal home agent 9. Since the GGSN4 carries out a test to determine whether the subscriber home addressused in the MIP HA registration request matches the IP address of thePDP context being used, the authentication and authorization function isprovided in a simple manner. In a situation where the signaling of themobile terminal 7 took place via the WLAN 3, the GGSN 4 has to checkwhether there is a valid PDP context for the mobile terminal 7 andwhether the mobile terminal 7, and hence its IP-mt, is authenticated andauthorized to use a desired service. The mobile IP registration requestshould include not only the IP address but also further identities ofthe mobile subscriber, in order to prevent the IP address from beingused by unauthorized subscribers. The integrated home agent 9 sets up anMIP tunnel 6 as a new data path to the LMA 5. All of the downlinktraffic or specific data streams is or are then passed via this tunnel 6on the basis of the traffic flow template. End of service signaling canbe carried out on the old data path 10 in order to specify the datacoordination in the mobile terminal 7. The GGSN 4 carries out thecharging of the new data path, that is to say via the tunnel 6, as anextra, characterized, for example, as a new QoS class. As soon as thenew data path has been set up via the tunnel 6, the mobile terminal 7can also use it for the uplink traffic. The LMA 5 tunnels all of theuplink data to the GGSN 4. In addition to the function of a foreignagent, which de-encapsulates the downlink traffic, the LMA 5 also has toencapsulate all of the uplink traffic and send it in the tunnel 6 to theGGSN 4 or to the integrated home agent 9, in order to allow completecharging there. This function is referred to as reverse tunneling. Atthe same time, it has to prevent the mobile terminal 7 from carrying outroute optimization and, in the process, allowing direct routing betweenthe LMA 5 and a correspondent host 11 without passing through the GGSN 4and the home agent 9. This can be achieved by the corresponding MIPmessages being rejected or being negatively acknowledged by routeoptimization for the mobile terminal 7 by the LMA 5.

1. A heterogeneous mobile radio system (1) for provision of servicesfrom a packet data network for a mobile terminal (MT) (7) having atleast one first mobile radio network (2) and one second mobile radionetwork (3), with the mobile radio networks (2, 3) each having at leastone access node (4, 5) to the packet data network, and in which case theaccess node (5) for the second mobile radio network (3) can be connectedto the packet data network only indirectly via the access node (4) forthe first mobile radio network (2).
 2. The heterogeneous mobile radiosystem (1) as claimed in claim 1, characterized in that the first mobileradio network (2) is a 2G/3G mobile radio network, and/or the secondmobile radio network (3) is a local transmission network, in particulara WLAN.
 3. The heterogeneous mobile radio system as claimed in claim 1or 2, characterized in that the packet data network is the Internet. 4.The heterogeneous mobile radio system as claimed in one of the precedingclaims, characterized in that the first mobile radio network (2)represents an overlay network for the second mobile radio network (3).5. The heterogeneous mobile radio system as claimed in one of thepreceding claims, characterized in that at least one agent function, inparticular a “home agent” function, can be integrated in the access node(4) for the first mobile radio network (2).
 6. The heterogeneous mobileradio system as claimed in claim 5, characterized in that, when using ahome agent function, in particular a mobile IP home agent function, datawhich can be specified is selectively transmitted only via the secondmobile radio network.
 7. The heterogeneous mobile radio system asclaimed in one of the preceding claims, characterized in that theindirect connection between the access network node (5) for the secondmobile radio network (3) and the packet data network can be provided bytunneling of data between the access network node (5) for the secondmobile radio network (3) and the access node (4) for the first mobileradio network (2) by means of suitable protocols, in particular by meansof MIP and/or GTP.
 8. The heterogeneous mobile radio system as claimedin one of the preceding claims, characterized in that a control functionis provided in the access node (5) for the second mobile radio network(3) and causes data packets which are to be sent from the second mobileradio network (3) to be transported exclusively to the access node (4)for the first mobile radio network (2).
 9. A method for provision ofservices from a packet data network for a mobile terminal (7) in amobile radio system, with the method having at least the followingsteps: a. provision of at least one first (2) and one second (3) mobileradio network, each having at least one access node (4, 5) to the packetdata network; b. combination of the mobile radio networks (2, 3) suchthat data packets can be transported between the second mobile radionetwork (3) and the packet data network only indirectly via the accessnode (4) for the first mobile radio network (2).
 10. The method asclaimed in claim 9, characterized in that the provision of a controlfunction in the access node (5) for the second mobile radio network (3)results in data packets which are to be sent from the second mobileradio network (3) being transported exclusively to the access node (4)for the first mobile radio network (2).
 11. The method as claimed inclaim 9 or 10, characterized in that charging for use of the secondmobile radio network is carried out in the first mobile radio network.12. The method as claimed in one of claims 9 to 11, characterized inthat authentication and authorization of a subscriber for use of thesecond mobile radio network are carried out in the first mobile radionetwork.
 13. A mobile terminal for use of a heterogeneous mobile radiosystem having at least one first mobile radio network and one secondmobile radio network, in which case the mobile terminal cansimultaneously maintain connections for the first and for the secondmobile radio network.
 14. The mobile terminal as claimed in claim 13,characterized in that the mobile terminal can selectively transmit datavia the first and/or via the second mobile radio network.
 15. The mobileterminal as claimed in claim 13 or 14, characterized in that datastreams which are transported via the first and the second mobile radionetwork can be combined in the mobile terminal.